NAME

       dwz - DWARF optimization and duplicate removal tool

SYNOPSIS

       dwz [OPTION...] [FILES]

DESCRIPTION

       dwz  is  a  program that attempts to optimize DWARF debugging information contained in ELF
       shared  libraries  and  ELF  executables  for  size,  by   replacing   DWARF   information
       representation  with  equivalent smaller representation where possible and by reducing the
       amount of  duplication  using  techniques  from  DWARF  standard  appendix  E  -  creating
       DW_TAG_partial_unit   compilation   units  (CUs)  for  duplicated  information  and  using
       DW_TAG_imported_unit to import it into each CU that needs it.

       The tool handles DWARF 32-bit format debugging sections of versions 2, 3  and  4  and  GNU
       extensions  on  top  of  those,  though  using  DWARF  4 or worst case DWARF 3 is strongly
       recommended.

       The tool has two main modes of operation, without the -m option it  attempts  to  optimize
       DWARF   debugging  information  in  each  given  object  (executable  or  shared  library)
       individually, with the -m option it afterwards attempts to optimize even  more  by  moving
       DWARF  debugging  information entries (DIEs), strings and macro descriptions duplicated in
       more than one object into a newly created ELF ET_REL object whose filename is given as  -m
       option  argument.  The debug sections in the executables and shared libraries specified on
       the command line are then modified again, referring to the entities in the  newly  created
       object.

OPTIONS

       -m FILE --multifile FILE
              Multifile  mode.   After  processing  all  named  executables and shared libraries,
              attempt to create ELF object FILE and put debugging information duplicated in  more
              than  one object there, afterwards optimize each named executable or shared library
              even further if possible.

       -h --hardlink
              Look for executables or shared libraries hardlinked together, instead of  rewriting
              them  individually  rewrite just one of them and hardlink the rest to the first one
              again.

       -M NAME --multifile-name NAME
              Specify the name of the common file that should be put into  the  .gnu_debugaltlink
              section alongside with its build ID.  By default dwz puts there the argument of the
              -m option.

       -r --relative
              Specify that the name of the common file  to  be  put  into  the  .gnu_debugaltlink
              section  is  supposed  to  be  relative  path  from  the  directory  containing the
              executable or shared library to the file named in the argument of  the  -m  option.
              Either -M or -r option can be specified, but not both.

       -q --quiet
              Silence up some of the most common messages.

       -o FILE --output FILE
              This  option  instructs  dwz not to overwrite the specified file, but instead store
              the new content into FILE.  Nothing is written if  dwz  exits  with  non-zero  exit
              code.  Can be used only with a single executable or shared library (if there are no
              arguments at all, a.out is assumed).

       -l COUNT --low-mem-die-limit COUNT
              Handle executables  or  shared  libraries  containing  more  than  COUNT  debugging
              information  entries  in  their  .debug_info section using a slower and more memory
              usage friendly mode and don't attempt to optimize that object  in  multifile  mode.
              The  default  is  10  million DIEs.  There is a risk that for very large amounts of
              debugging information in a single shared library or executable there might  not  be
              enough  memory  (especially  when  dwz  tool  is 32-bit binary, it might run out of
              available virtual address space even sooner).

       -L COUNT --max-die-limit COUNT
              Don't attempt to optimize executables or  shared  libraries  containing  more  than
              COUNT DIEs at all.  The default is 50 million DIEs.

       -? --help
              Print short help and exit.

       -v --version
              Print version number and short licensing notice and exit.

ARGUMENTS

       Command-line  arguments  should  be the executables, shared libraries or their stripped to
       file separate debug information objects.

EXAMPLES

              $ dwz -m .dwz/foobar-1.2.debug -rh \
                bin/foo.debug bin/foo2.debug foo/lib/libbar.so.debug
       will attempt to  optimize  debugging  information  in  bin/foo.debug,  bin/foo2.debug  and
       lib/libbar.so.debug (by modifying the files in place) and when beneficial also will create
       .dwz/foobar-1.2.debug file.  .gnu_debugaltlink section in the first two files  will  refer
       to  ../.dwz/foobar-1.2.debug and in the last file to ../../.dwz/foobar-1.2.debug.  If e.g.
       bin/foo.debug  and  bin/foo2.debug  were  hardlinked  together  initially,  they  will  be
       hardlinked  again  and for multifile optimizations considered just as a single file rather
       than two.
              $ dwz -o foo.dwz foo
       will not modify foo but instead store the ELF object with optimized debugging  information
       if successful into foo.dwz file it creates.
              $ dwz *.debug foo/*.debug
       will  attempt  to  optimize  debugging  information  in  *.debug  and  foo/*.debug  files,
       optimizing each file individually in place.
              $ dwz
       is equivalent to dwz a.out command.

SEE ALSO

       http://dwarfstd.org/doc/DWARF4.pdf , gdb(1).

AUTHORS

       Jakub Jelinek <jakub@redhat.com>.

                                           15 June 2012                                    dwz(1)